Spark-plug tester.



c. E. HARLAN. I

SPARK PLUG TESTER.

v APPLICATIONTILED ms. 19. m6.

i 2 %9,953. Patented Dec.11,191?.

WITNESSES: I? I M M V 2) III INVENTOR 8224x20 .fifa/"Zan w/ HM Amonmm GLEJUKE E, HARLAN, F "WATSON'VILLE, CALIFORNIA.

SPARK-PLUG TESTER.

Specification of Letters Eatent.

Patented Dee. fill, 191*? Application filed February 19, 1916. Serial No. 79,324.

oif'the ehjectsof the present invention provide simple, portable testing infi trouble in the ignition combustion engines for re whether the trouble plug, a short circuit in r ions, punctured insulation, .e, Another object of the Lion to provide means for sistanee to the passage of the e several plugs and conher sets will hereincombination of parts as ully described and claimed, the accompanying drawv tiers. 3o

rring the drawings indetail,.A incates a frame which is adapted to be setensions 2.

he frame a cross-bar 3, net-ed of an insulating maporcelain, or the like, crossbar is a plurality of 1 is to n insulating scour d thereon aplurality s 6 re loo prefe material and has e o sparking poin iounted in direct allne- .rring points l on the staoller is preferably hrough the ts oil? the parts and the on the en ine b means of a 0 1 itigidly seroller in adjusted position. Turnably mounted in the frame, above the stationary crossbar, in amanner similar to the lower roller 5, is a roller 9, also constructed of insulating material and provided with a handle 10 and a set-screw 11 to lock it against turning movement.

Suitably secured on the roller 9 is a metal plate extending the entire length of the roller and having its ends contacting with the frame to form a ground circuit therewith, as Will hereinafter be described. This bar Will hereinafter be termed the resistance bar 12.

In operation, when it is desired to locate any trouble in the ignition circuit, it is acshown in Fig. 2, and the terminals 16 of the sparking points 6 are connected by wires 17 with their individual spark plugs; the

ground of the magneto being connected by means of a wire 18 with any suitable contact on the engine in the usual manner. The engine can now be started and is preferably made to run at a comparati ely slow speed while certain tests are being conducted.

The electric current generated by the magneto, in order to complete its circuit through the en ine plugs, will have to jump the ap formed between the sparking points 4: and 6. The current flow can thus be observed at this point. The distance between the sparking points is gradually increased as the test is progressing by turning the roller 5, by means of the handle 7 until the gap produced approximates a half inch or more. If the current continues to jump between the several sparking points, after a half inch ap has been secured, it will immediately indicate that the magneto, with connected wiring and spark plugs, is in good condition and. proper working order and that engine troubles, if any, will have to be looked for in some other place.

if the spark becomes extinguished hetween any one set of sparking points 4 and 6, when a half inch gap has been secured or previous thereto, it will immediately iudicate that something is wrong in this cir creased no can pass the theengine is running unoler a sin 5 r instance, leakage may occur wiring *onnections or the c n in the: distributor of the too far apart or may be partly oclerl, or a short circuit in the connections may he found. The testing instrument will in all cases indicate the defective circuit, making it comparatively easy to locate the actual defect. It can, therefore, he seen that if any connections between the engine plugs and magneto are short-circuited or otherwise defective, as the distance between the sparking points increases, the resistance to the passage of current will become so great that the spark in the defective circuit Will immediately become extinguisheoi, as the current in the defective circuit will not he strong enough to jump the Y A gap hetigeen he spark ng plugs. 13 L One or tne important features or the present invention is the provision of the resistm l ance car 12. M118 is employed ror the purpose of testing the resistance to the passage of current through the spark plugs, with" I -ectecl Wiring, anol 1s accomplishes-cl. by 1 b g the roller 9 until the her 12 asso we the full line position shown in Fig. 1. "Vtlith the engine runnlng at slow speed low compression is created in the engine cylinders anal resistance to the current uniping the gaps n the plugsus comparatively sinail. lln this instance it is possible to nl b.,.,1 L t l k JQ niGWo me at to a point approxinia Us or inch away from the sparking points i.

I the hefore the spark Will leave the gap plug terminals anol jump across to the her is grounded with relation to magneto. it has been found that for some reason some spark plugs are natuily h hiy resistant to the flow or? curresistance is again oiten in creased by corrosion on the sparking points or slight coating of carbon on A plug thus e'liectec. causes consiclerahle trouble in an engine as it Will the r m {L 3! L L f2 A I speak to ump the points or the plug wnen ah low compression and will, therefore,

oppeatrances he in perfect working or n however, will he so resista the or that the moment one load or cont sion of engine is in- Wiil then jumpv across to the ing her and in. some instances jumps the ace of a half inch or more, immediately indicating that the connected plug is either corroded, coated With a carbon or otherwise resistant to the passage or the; current.

This defect can sometimes be overcome by hrough the ping y removing cause of tronhls,

of some generators or the The 7 means for connec In a prac in condition, it is tonne an inch spacing between the resistance bar and the points l must be reached before the spark Will leave the plug points and jump across to the bar, but any defective plug, or one that is resistant to the current, Will begin to jump across the long heiiore a of an inch spacing is secured; thus inclicating immediately which plug is defective.

The construction of the testing instrument here shown permits the ignition systern of any internal combustion eigins to he tested While the engine is running, and also eliminates the necessity of removing the on gins plugs While the test is being rnadew The test although preferably made low speed as the spark can then. he most easily observed, can he rnacie various engine speeds; this being ii portant feature of the present invention as the our ent out; I niagnetcs varies greatl With the change speech Whiie the speciticatio describe current jumping a on" 1 1c o vorahle condi ions this distance is magneto may :Iurn n unoier same conditions r as make only p a or inch and c the testing tne experience a manufacturer may clici Wish it unclerstooi in form, proportions and cl construction may he reso ted to scope of the apps 4 not Wish to limit si and L .i cla ent i 1. he corne s Jarlr oing mounted on insole a plurality of sparking points a the seconoai .L e 1 J. new and toe other With the spark plu s 3. The combination with an internal combustion engine, of a spark plug tester comprising a frame adapted to be grounded to the engine, a stationary roller secured in and insulated from the frame, a plurality of sparking points secured on said roller and insulated from each other, a turnable roller mounted in the frame and insulated therefrom, a plurality of sparking points secured on said roller and insulated from each'other, a second roller turnably mounted in the frame and grounded thereto, and a resistance bar carried by said roller adapted to be moved into and out of engagement with the sparking points on the stationary roller when 'the roller upon which it is mounted is turned.

4. The combination with an internal combustion engine, of a spark plug tester comprising a frame adapted to be grounded to the engine, a stationary roller secured in and insulated from the frame, a plurality of sparking points secured on sald roller and insulated from each other, a turnable roller mounted in the frame and insulated first named turnable roller against move ment, and means for lockingthe second named turnable roller against movement.

5. A device of the character described comprising a frame, a plurality of double contact members carried by said frame and connected with one side of a source of electrical energy, a resistance testing member connected with the other side of said source of said double contact members.

6. A sparking indicator comprising, i combination, a stationary holder, a movable holder adjustably mounted on same, a plurality of sparking points secured on the stationary holder and insulated from same, a plurality of sparking points secured on the movable holder and insulated from same, means for connecting the sparking points on the movable holder with the secondary wires of a magneto, means for connecting the sparking points on the stationary holder with the spark plugs on an internal combustion engine, and a grounding bar adjustably mounted with relation to the spark- 1ng points on the movable holder, said grounding bar being grounded with relation to the magneto.

7. A device of the character described comprising a frame, a plur'alit of double contact members carried by sai frame and connected with" one side of a source of electrical energy, a resistance testing member connected with the other side of said source and movable toand from the upper sides of said double contact members,-a plurality 10f single contact members movable into electrical connection with the lower sides of said double contact members, and means for locking said double contact members and said resistance testing member in adjusted position.

In testimony whereof I have hereunto set I myhand in the presence of two subscribing I witnesses.

GLAUD E. EAR-LAN. Witnesses: CHAS. E. BLOOM,

BEATRICE S. GoUeH. 

